1985 12A, Nippondenso compressor.............ran a jumper from the battery as the postings suggested and got the compressor to turn over, but it turns real slow, not fully engaging with the speed of the belt. Good spark from the jumper wire, so I think it's drawing lots of juice. Gauge on low side reads 40, using one of the refiller kits.

Light on the dash comes on, engine idle climbs when a/c button pushed and light comes on at the dash, but without the jumper wire compressor doesn't engage. A pressure switch I guess.

Does the a/c not fully turning mean a clutch?, compressor, problem or what? compressor clutch turns easily by hand.

thoughts...........thanks.